Future Energy Sources 1.9.2.1 Hot Fusion

The only technology which seems more practical for the long term is solar. Solar has even a worse track record for feasible large power production. Though practical fusion is always only a decade away, practical solar is always only a few years away, as it has been for the last few decades.

Apart from little problems like what do we do when the sun is not out or what do we do when the isn't shinning like at night, solar may be part of the solution. Unlike fusion, photovoltaic cells do work but they are as expensive as sin (and sin could cost you your soul), currently photovoltaic cells are the most expensive way on earth to create electrical current. Maybe we could use photovoltaics to generate oxygen and hydrogen by electrolysis of water and the store the hyrdogen to be burned in vehicles or used in fuel cells to create electricity when the demand for electricity does not follow the same schedule as the availability of useful quantities of solar energy.

The way it looks now each fusion plant or group of plants will require an onsite nuclear fission site as a sort of starter motor so to speak at least until we got the first one going, then we could boot strap the rest of the fusion reactors until they were all going. In a tremendous act of self control I will refrain from suggesting a CANDU system as the logical choice for such a "starter motor". The small quantities of tritium produced in a nuclear reactor could also be used as fuel in a fusion reactor.

One question that bothers me though is will there be any sort of throttle on a fusion reactor? Given the difficulty starting and maintaining the plasma at the temperatures required will it only have two settings, stopped and flat out. How would it be controlled to meet fluctuating demands on the grid?

When it comes time to decommision the fusion reactor you could store the by now highly radioactive portions of it with the spent fuel from the fission reactor.

Fusion has much to be said for it but if the dirty little secret gets out that it is the same process that is used in the hydrogen bomb, there will be a knee jerk reaction among the public fearing mushroom clouds over our cities from Tokamaks run amuck. There are probably those who would feel that this even too dangerous an area to even be researching.

Hi,

there are 4 ways to nuclear fusion:

1. inside the stars at incredible pressure and temperature,

2. in the hydrogen bomb at similar conditions but in reality working with tritium and lithium and to be ignited by a nuclear bomb and burning uncontrolled,

3. in the tokamak or stellarator or similar ringlike plasma structures: in a vacuum, with injected preionized tritium heated to more than 100million degrees!!!

4. in the laser experiments of the National Ignition Facility (NIF) where a laser system as big as 16? football places is focused onto a tiny hollow glass sphere 0.2mm diameter to heat and compress to the same incredible temperatures.

5. May be also by the so called "cold fusion" that is debated, but not very likely to really exist, and if existing not likely to gain energy from.

Possibilities 1 and 2 are reality, possibility 3 was reality for some milliseconds to maximum 1 second in the last experiment in England (JET) but after this short period of burning the ring is so highly radioactive that it cannot be touched again.

Possibility 4 is planned and built since the early 90ies and I pretend that the ease of financing has nothing to do with energy gain but with the early stages of nuclear weapon ignition.

Since the first plans for controlled fusion - changing the energy gain by changing the plasma temperature or pressure or constitution or heating for control - the physical community claimed a time to reality of 40 to 50 years. As this is going on since 50years nobody can make a guess if this approach will be ever working and how much radioactivity it will produce.

There will be an extremely high neutron flux inside the plasma tube and the neutrons will be captured by the inner lining of the plasma tube converting the atoms to other species some of these being radioactive, some being very dirty and some with long life and bad radioactivity.

So not only burning this type of reator will be critical but also providing an ultrapure inner lining (a blanket) of lithium for the plasma tube.

If ever this system will work not earlyer than 2060.

So we will be wise not to rely on it.

Financing the next test machine has been agreed on (google for ITER) with cost between 10 and 20 billion $!!!

Possibility No.4 is not better but very likely to be worse. This will operate within the next 5 years. So this approach too is not very likely to be energy producing in time to be a solution for a possible oil and gas shortage.

So my conclusion will be: get financing ready for further research but do not rely on it.

Happy Easter and or Pessah and or Holidays

RHABE

Fusion looks to me as the wet dream of nuclear scientists, nice to prove that it works but I fear that they will tell us in 100 years or so that the system is not usable as an energy source here on earth. Unless some extra efforts could be paid for.

The whole proces is so powerfull, I fear that we will have uncontrollable reactions happening as soon as the systems work.

Something on the sideline: how will they refuel after the first seconds of function, the reacting mass will always be low, so the initial reaction will be nice but the fusible stuff will be consumed very quickly, needing new and creating a need to get the fusion products out of the process.

I think at worst this could be akin to the space efforts of the 1950s-1960s. Still no signs of them meeting their original objectives, but I believe they have paid for themselves several times over in terms of spins-off.

My expectation would be that the spin-off from fusion research will be less dramatic than from developing space technology; on the other hand, there's a reasonable chance that fusion will become a viable technology somewhere in the second half of this century - by which time we may need to work with zero emissions of greenhouse gases - or even to remove some of the CO2 we've created between now and then. I'm with RHABE that fusion probably won't be nearly as clean as some would have us believe - but at least most of the by-products will decay much faster than fusion by-products. I think we need to fund it adequately, but not to the exclusion of nearer-term measures.

On which subject, my understanding is that, even in respect of radiative by-products, coal is significantly worse even than fission - so perhaps it is time we were more realistic about that too.

Fyz

Just came across a Google Video on "Inertial Electrostatic Fusion" called:

Should Google Go Nuclear? Clean, cheap, nuclear power (no, really)

It's a fairly long 1hr, 33min presentation, interesting and recent, and another fusion path.

See also:

http://www.askmar.com/ConferenceNotes/2006-9%20IAC%20Paper.pdf

Although Proton + B11 -> 3He4 +energy is a reaction that is relatively easy to keep "clean" (it produces relatively few high-energy neutrons), there are other issues. The Wikipedia article on Aneutronic fusion approximates the present consensus.

The approach is mainly supported by the space industry, rather than by nuclear energy workers. The reason for their interest is that the momentum imparted to the He product is relatively large.

BTW - nomenclature - who would define a process "two atoms -> three atoms" as fusion??

Fyz

Read the article. That and Dr. Bussards video and papers are outside of my area of expertise.

I did come across http://epaper.kek.jp/p93/PDF/PAC1993_0700.PDF, which suggest using accelerators to achieve the 675 KeV energy max cross-section point. Couldn't tell anything about net energy from what I read.

Maybe both physics and engineering might still be necessary for the polywell.

Understand the BTW; guess one could talk about n + U235 fusion as well.

One MeV or less is quite easily achieved using electrostatics and refocusing as well. The issues lie in confinement and in the efficiencies of the overall processes, and I'm not convinced that accelerators are better (or necessarily worse) than voltage multipliers in this case. The energy issues lie partly in the preprocessing as well. 12:1 one sounds a large gain, but we have to have a stimulation port etc, and thermal-to-electrical conversion, which leaves about 4:1 to spare.

I'm not knowledgeable or wise enough to make these judgements - hopefully time will tell.

Fyz